Question

Wobbe Index is a characteristic of ________
A.Solid fuels
B.Gaseous fuels
C.Liquid fuels
D.Fat Coals

Answer 1

Hint: Wobbe Index is also known as the Wobbe number that is used to measure the interchangeability of the gaseous fuels. It indicates if a turbine can run on the specified alternative fuel source without making any physical modification to the machine.

Complete answer:
We know the definition of the Wobbe Index as mentioned above, let’s understand its Mathematical meaning.
The Wobbe index is the ratio of the higher heating value and the specific gravity/ relative density. It is calculated by using the magnitude of higher heating value and relative density.
${{I}_{w}}\text{ = }\dfrac{Higher\text{ heating value}}{\operatorname{Re}lative\text{ density or Specific gravity}}$
Where, ${{I}_{w}}$ is the Wobbe Index.
Here,
Higher heating value is the amount of heat that is released during the combustion of a specific gas. It can also be stated as the higher calorific value. The SI unit is kcal.
Specific gravity or relative density is the ratio of the density of the given substance to the density of the reference substance. The specific gravity of gases is measured in the reference to the air that is present at room temperature and fixed pressure.
Thus, the correct answer is Option B- Gaseous fuels.

Additional information: The fuels with the same Wobbe index will give an equal amount of energy output. If the Wobbe index of the fuel is very high, the energy will be more and the fuel will require more oxygen for its combustion. This will eventually impact negatively on the environment.

Note:
Wobbe index is an important distinguishing feature of Gaseous fuels. It gives a relation between the heating feature of the mixed fuel gases. It is also used to find the constant heat flow from gases that comprise different compositions of gas.